In this study forest fallows (locally known as purmas) are classified and described in three categories: natural fallow succession (PS), degrading fallow vegetation (PD) and fallow dominated by kudzu (Pueraria phaseoloides) (PK). The study area of Semuya has 83% under PS, and the area of Nueva Requena 25% and 20.5% of fallows belonging to PD and PK, respectively. Around 70% of surveyed fallows are less than 4 years old. The impact of land use patterns on secondary vegetation was expressed in changes in the floristic composition and the potential use of the forest fallows. In Nueva Requena, where a larger land area covered by degrading fallow vegetation was found, annual crops, mainly rice and cassava, were the dominant land use pattern. It is concluded that external conditioning factors, such as incentive policies for agriculture, social unrest and livestock expansion, contributed to the accelerated degradation of secondary vegetation in the zone.